Add support for Bazel

Add examples/bazel with a sample downstream use, licensed as MIT-0.

Other fixes:
- Adjust lcm_eventlog.py test to not require copying the example log.
- Fix a small typo in the go example.

.bazelignore

@@ -0,0 +1,2 @@
+# When traversing //... don't incorporate the example.
+examples/bazel

.bazelversion

@@ -0,0 +1 @@
+8.0.1

.github/workflows/test_bazel.yml

@@ -0,0 +1,22 @@
+name: test_bazel
+
+on: [push, pull_request]
+
+jobs:
+  bazel:
+    strategy:
+      matrix:
+        os: [ubuntu-24.04, macos-14]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v4
+    - uses: bazel-contrib/setup-bazel@0.13.0
+      with:
+        bazelisk-cache: true
+        disk-cache: ${{ github.workflow }}
+        repository-cache: true
+    - name: Test Main
+      run : 'bazel test //...'
+    - name: Test Example
+      working-directory: examples/bazel
+      run : 'bazel test //...'

.gitignore

@@ -1,6 +1,8 @@
 build*/
 __pycache__
 docs/_build/
+bazel-*
+MODULE.bazel.lock
 
 .vscode/
 .idea/

BUILD.bazel

@@ -0,0 +1,16 @@
+load("@rules_license//rules:license.bzl", "license")
+
+package(
+    default_applicable_licenses = [":license"],
+    default_visibility = ["//visibility:public"],
+)
+
+exports_files([
+    "COPYING",
+])
+
+license(
+    name = "license",
+    license_kinds = ["@rules_license//licenses/spdx:LGPL-2.1"],
+    license_text = "COPYING",
+)

MODULE.bazel

@@ -0,0 +1,39 @@
+# This file specifies a Bazel workspace (see https://bazel.build/).
+#
+# For now, LCM's Bazel build only supports C, C++, Java, and Python.
+# We invite users to submit pull requests for other languages if needed.
+
+module(
+    name = "lcm",
+    bazel_compatibility = [">=8.0.1"],
+)
+
+# Load bazel rules.
+
+bazel_dep(name = "apple_support", version = "1.17.1", repo_name = "build_bazel_apple_support")
+bazel_dep(name = "bazel_skylib", version = "1.7.1")
+bazel_dep(name = "platforms", version = "0.0.10")
+bazel_dep(name = "rules_cc", version = "0.0.17")
+bazel_dep(name = "rules_java", version = "8.6.1")
+bazel_dep(name = "rules_jvm_external", version = "6.6")
+bazel_dep(name = "rules_license", version = "1.0.0")
+bazel_dep(name = "rules_python", version = "0.40.0")
+
+# Load runtime dependencies.
+
+bazel_dep(name = "pcre2", version = "10.45")
+bazel_dep(name = "glib", version = "2.82.2.bcr.1")
+
+maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")
+maven.install(
+    name = "lcm_maven",
+    artifacts = [
+        "junit:junit:4.11",
+        "net.sf.jchart2d:jchart2d:3.3.2",
+    ],
+)
+use_repo(maven, "lcm_maven")
+
+# Load dev dependencies.
+
+bazel_dep(name = "googletest", version = "1.15.2", dev_dependency = True)

docs/content/build-instructions.md

@@ -192,3 +192,16 @@ In addition, `pkgconfig` can be configured to find lcm.pc:
 ```shell
 export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:$LCM_LIBRARY_DIR/pkgconfig
 ```
+
+## Bazel
+
+LCM also supports [Bazel](https://bazel.build/) for a subset of languages
+(C, C++, Java, Python). The Bazel build only provides libraries and command
+line tools; it doesn't support building wheels or documentation.
+
+The Bazel build uses very few system packages, so most of the text above about
+required packages does not apply. The only required tool is a C/C++ compiler,
+e.g., `apt install build-essential` on Ubuntu and Debian. If Java will
+be used, a local JDK is also recommended, e.g., `apt install default-jdk`.
+See the [example](https://github.com/lcm-proj/lcm/tree/master/examples/bazel)
+for details.

examples/.gitignore

@@ -20,3 +20,6 @@
 /cpp/lcm_log_writer/pronto/
 /java/temperature_demo_java/lcmtypes/
 !/go/listener/
+
+# Don't ignore the bazel/exlcm source file symlinks.
+!bazel/exlcm/

examples/bazel/.bazelversion

@@ -0,0 +1 @@
+../../.bazelversion

examples/bazel/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: MIT-0
+
+bazel-*
+MODULE.bazel.lock

examples/bazel/BUILD.bazel

@@ -0,0 +1,132 @@
+# SPDX-License-Identifier: MIT-0
+#
+# Using LGPL-2.1 for examples leads to unnecessary hassle for users, so this
+# example is licensed under the https://spdx.org/licenses/MIT-0.html license,
+# except for the exlcm/*.lcm message definitions.
+
+load("@lcm//lcm-bazel:lcm_c_library_srcs.bzl", "lcm_c_library_srcs")
+load("@lcm//lcm-bazel:lcm_cc_library_srcs.bzl", "lcm_cc_library_srcs")
+load("@lcm//lcm-bazel:lcm_java_library_srcs.bzl", "lcm_java_library_srcs")
+load("@lcm//lcm-bazel:lcm_library.bzl", "lcm_library")
+load("@lcm//lcm-bazel:lcm_py_library_srcs.bzl", "lcm_py_library_srcs")
+load("@rules_cc//cc:cc_library.bzl", "cc_library")
+load("@rules_cc//cc:cc_test.bzl", "cc_test")
+load("@rules_java//java:java_binary.bzl", "java_binary")
+load("@rules_java//java:java_library.bzl", "java_library")
+load("@rules_license//rules:license.bzl", "license")
+load("@rules_python//python:py_library.bzl", "py_library")
+load("@rules_python//python:py_test.bzl", "py_test")
+
+package(
+    default_applicable_licenses = [":license"],
+    default_visibility = ["//visibility:public"],
+)
+
+exports_files([
+    "LICENSE.TXT",
+])
+
+license(
+    name = "license",
+    license_kinds = ["@rules_license//licenses/spdx:MIT-0"],
+    license_text = "LICENSE.TXT",
+)
+
+# Run lcm-gen on 'exlcm' for C, C++, Java, and Python.
+
+lcm_library(
+    name = "exlcm",
+    srcs = glob(["exlcm/*.lcm"]),
+    lcm_package = "exlcm",
+)
+
+lcm_c_library_srcs(
+    name = "exlcm_c_srcs",
+    src = ":exlcm",
+)
+
+cc_library(
+    name = "exlcm_c",
+    srcs = [":exlcm_c_srcs"],
+    deps = ["@lcm//lcm:lcm-static"],
+)
+
+lcm_cc_library_srcs(
+    name = "exlcm_cc_srcs",
+    src = ":exlcm",
+)
+
+cc_library(
+    name = "exlcm_cc",
+    srcs = [":exlcm_cc_srcs"],
+    deps = ["@lcm//lcm:lcm-coretypes"],
+)
+
+lcm_java_library_srcs(
+    name = "exlcm_java_srcs",
+    src = ":exlcm",
+)
+
+java_library(
+    name = "exlcm_java",
+    srcs = [":exlcm_java_srcs"],
+    deps = ["@lcm//lcm-java"],
+)
+
+lcm_py_library_srcs(
+    name = "exlcm_py_srcs",
+    src = ":exlcm",
+)
+
+py_library(
+    name = "exlcm_py",
+    srcs = [":exlcm_py_srcs"],
+    imports = ["."],
+)
+
+# Perform some basic testing on the generated messages.
+
+cc_test(
+    name = "test_c",
+    srcs = ["test_c.c"],
+    deps = [
+        ":exlcm_c",
+        "@lcm//lcm:lcm-static",
+    ],
+)
+
+cc_test(
+    name = "test_cc",
+    srcs = ["test_cc.cc"],
+    deps = [
+        ":exlcm_cc",
+        "@lcm//lcm:lcm-static",
+    ],
+)
+
+py_test(
+    name = "test_py",
+    srcs = ["test_py.py"],
+    deps = [
+        ":exlcm_py",
+        "@lcm//lcm-python",
+    ],
+)
+
+# Create aliases for the Java tools, adding our messages to the classpath.
+
+java_binary(
+    name = "lcm-spy",
+    main_class = "lcm.spy.Spy",
+    runtime_deps = [
+        ":exlcm_java",
+    ],
+)
+
+java_binary(
+    name = "lcm-logplayer-gui",
+    main_class = "lcm.logging.LogPlayer",
+    runtime_deps = [
+        ":exlcm_java",
+    ],
+)

examples/bazel/LICENSE.TXT

@@ -0,0 +1,12 @@
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

examples/bazel/MODULE.bazel

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: MIT-0
+
+bazel_dep(name = "lcm", version = "1.5.1")
+
+# This example uses lcm from our same git checkout. In most cases, you'll want
+# to remove this override in your own projects.
+local_path_override(
+    module_name = "lcm",
+    path = "../..",
+)
+
+bazel_dep(name = "rules_cc", version = "0.0.17")
+bazel_dep(name = "rules_java", version = "8.6.1")
+bazel_dep(name = "rules_license", version = "1.0.0")
+bazel_dep(name = "rules_python", version = "0.40.0")

examples/bazel/exlcm/example_list_t.lcm

@@ -0,0 +1 @@
+../../types/example_list_t.lcm

examples/bazel/exlcm/example_t.lcm

@@ -0,0 +1 @@
+../../types/example_t.lcm

examples/bazel/exlcm/exampleconst_t.lcm

@@ -0,0 +1 @@
+../../types/exampleconst_t.lcm

examples/bazel/exlcm/multidim_array_t.lcm

@@ -0,0 +1 @@
+../../types/multidim_array_t.lcm

examples/bazel/exlcm/node_t.lcm

@@ -0,0 +1 @@
+../../types/node_t.lcm

examples/bazel/test_c.c

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: MIT-0 */
+
+#include <lcm/lcm.h>
+#include <stdio.h>
+
+#include "exlcm_example_t.h"
+
+int main()
+{
+    exlcm_example_t message = {};
+    message.name = "";
+    const int size = exlcm_example_t_encoded_size(&message);
+    if (size != 82) {
+        fprintf(stderr, "size = %d\n", size);
+        fflush(stderr);
+        return 1;
+    }
+
+    lcm_t *memq = lcm_create("memq://");
+    int handled = -1;
+    if (memq != NULL) {
+        handled = lcm_handle_timeout(memq, 0);
+        lcm_destroy(memq);
+    }
+    if (handled != 0) {
+        fprintf(stderr, "memq failure\n");
+        fflush(stderr);
+        return 1;
+    }
+
+    return 0;
+}

examples/bazel/test_cc.cc

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: MIT-0 */
+
+#include <iostream>
+
+#include <lcm/lcm-cpp.hpp>
+
+#include "exlcm/example_t.hpp"
+
+int main() {
+  exlcm::example_t message = {};
+  const auto size = message.getEncodedSize();
+  if (size != 82) {
+    std::cerr << "size = " << size << "\n";
+    return 1;
+  }
+
+  lcm::LCM memq("memq://");
+  if (memq.handleTimeout(0) != 0) {
+    std::cerr << "memq failure\n";
+    return 1;
+  }
+
+  return 0;
+}

examples/bazel/test_py.py

@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: MIT-0
+
+import unittest
+
+import lcm
+
+from exlcm import example_t
+
+
+class TestPy(unittest.TestCase):
+    def test_size(self):
+        message = example_t()
+        size = len(message.encode())
+        self.assertEqual(size, 82)
+
+    def test_memq(self):
+        memq = lcm.LCM("memq://")
+        self.assertEqual(memq.handle_timeout(0), 0)
+
+
+def main():
+    unittest.main()
+
+
+assert __name__ == '__main__'
+main()

examples/go/gen.go

@@ -6,5 +6,5 @@ package exlcm
 //go:generate lcm-gen -g ../types/exampleconst_t.lcm
 //go:generate lcm-gen -g ../types/example_list_t.lcm
 //go:generate lcm-gen -g ../types/example_t.lcm
-//go:generate lcm-gen -g ../types/multidim_array_t.lcm
+//go:generate lcm-gen -g ../types/muldim_array_t.lcm
 //go:generate lcm-gen -g ../types/node_t.lcm

lcm-bazel/BUILD.bazel

@@ -0,0 +1,4 @@
+package(
+    default_applicable_licenses = ["//:license"],
+    default_visibility = ["//visibility:private"],
+)